Linked from
The 30 pages that link to Prime-counting function, each with the reason it gives.
Prime gapsRelated: Its local changes reveal how many primes, and thus gaps, occur in an interval.
Sieve of EratosthenesRelated: Counting the sieve’s survivors directly gives π(x) for a chosen limit.
Integer sequenceRelated: Its values form an integer sequence recording the distribution of primes.
Legendre's conjectureRelated: Its values express the claim as π((n+1)²) − π(n²) ≥ 1.
Bonse's inequalityRelated: It describes how many factors enter the primorial as its endpoint grows.